An embodiment relates generally to identifying an adhesive effect of the road surface upon which a vehicle is traveling.
Road surface condition identification has been mainly through remote-sensing measurement based on the reflection and absorption characteristics of the road pavement utilizing various methods including microwave and optical sensing techniques. However, this approach can be rather complicated since the frictional characteristics of the detected surfaces are largely dependent on a combination of surface pattern, strength, and elasticity, and even surface temperature, in addition to extra cost on the sensors and processors. On the other hand, road surface condition can also be inferred from the estimation of road surface friction. But this approach typically requires evasive maneuvers so that tire operates under nonlinear or near-limit region. Therefore, it is often not very practical since many active safety and driver-assist features mainly operate under normal driving maneuvers that do not generate the needed large excitation for the tire to operate in nonlinear or near limit region. In addition, this approach typically requires extra sensors, such as corner force measurement.